Method for preparing a catalyst suitable for polymerizing an olefin

ABSTRACT

A method for polymerizing at least one olefin by contacting at least one olefin with a polymerization catalyst and an organometallic compound containing a metal from group 1, 2, 12 or 13 of the Periodic System of Elements under effective polymerization conditions. The polymerization catalyst is obtained by contacting metallic magnesium with an aromatic halide, RX, under conditions effective to obtain a first reaction product and solid residual products. The first reaction product is then separated from the solid residual products. A silane compound containing an alkoxy or aryloxy group is added to the first reaction product between -20° C. to 20° C. to obtain a precipitate which is purified to obtain a second reaction product. Subsequently, the second reaction product is contacted with a halogenized titanium compound, such as titanium tetrachloride, to obtain a further reaction product. The polymerization catalyst is obtained by purifying the further reaction product. In the aromatic halide, R represents an aromatic group containing from 6 to 20 carbon atoms and X represents a halide.

RELATED APPLICATIONS

This application is a continuation/PCT/NL96/00151 filed Apr. 9, 1996,which is a continuation-in-part of PCT/NL95/00132, filed Apr. 10, 1995,the complete disclosures of which are incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a method for the preparation of a catalystsuitable for the polymerisation of an olefins by contacting a magnesiumcompound with a halogenized Ti-compound.

BACKGROUND INFORMATION

Such a method is known from NL-A-7805523, which discloses, amongst otherthings, that a catalyst suited to the polymerisation of olefins can beobtained by contacting a magnesium compound, which is obtained byreacting during one reaction step metallic magnesium with an organichalide RX, where R is an alkyl, alkenyl, aryl or cycloalkyl groupcontaining from 1 to 20 carbon atoms, and X is a halogen, and an alkoxygroup or aryloxy group-containing silane compound with a halogenizedTi-compound.

SUMMARY AND OBJECTS OF THE INVENTION

A drawback of the aforementioned method for the preparation of thecatalyst is that the activity of the catalyst obtained is poor. The aimof the invention is to obtain a method for the preparation of thecatalyst in which this drawback does not occur.

The invention is characterised in that:

the magnesium compound is obtained by:

a) contacting metallic magnesium with an aromatic halide RX, where R isan aromatic group containing from 6 to 20 carbon atoms and X is ahalogen, whereupon the dissolved reaction product I is separated fromthe solid residual products and then

b) adding an alkoxy group or aryloxy group-containing silane compound tothe obtained reaction product I at a temperature of from -20 to 20° C.,whereupon the precipitate is purified to obtain reaction product II,

which subsequently, during a step c, is contacted with TiCl₄ ashalogenized Ti-compound and is purified to obtain a catalyst.

In this way a highly active catalyst is obtained.

A further advantage of the catalyst obtained by the process describedabove is that, when used for the polymerization of propylene, thiscatalyst yields a polypropylene which is highly isotactic. Furthermore,the polyolefin powder produced with the catalyst of the inventioncontains few small particles.

From EP-A-0,319,227 a similar method is known for the production of acatalyst suitable for the polymerization of an olefin. According to thispatent publication, however, it is necessary to carry out an extrareaction step using a halogen-containing alcohol if a catalystexhibiting good activity is to be obtained.

DETAILED DESCRIPTION OF THE INVENTION

The first step in the process for the preparation of the catalyst of theinvention is carried out by contacting metallic magnesium with anaromatic halide RX.

All forms of metallic magnesium may be used as metallic magnesium, butpreferably use is made of finely divided metallic magnesium, for examplemagnesium powder. To obtain a fast reaction it is preferable to heat themagnesium under nitrogen prior to use. In the aromatic halide RX, R isan aromatic group preferably containing from 6 to 18 carbon atoms and Xpreferably is chlorine or bromine. Chlorobenzene, bromobenzene andiodinebenzene can be mentioned as examples. Preferably chlorobenzene isused as the aromatic halide RX.

The magnesium and the aromatic halide RX are preferably brought intocontact with one another in the presence of an inert dispersant and anether. Examples of dispersants are: aliphatic, alicyclic or aromaticsolvents containing 4-10 carbon atoms. Examples of ethers are:

diethyl ether, diisopropyl ether, dibutyl ether, diisobutyl ether,diisoamyl ether, diallyl ether, tetrahydrofuran (THF) and anisole. It ispreferred for dibutyl ether and/or diisoamyl ether to be used.

Preferably, chlorobenzene is used as dispersant. Thus, the chlorobenzeneserves as dispersant as well as aromatic halide RX.

The aromatic halide/ether ratio is important with respect to obtainingan active catalyst. The chlorobenzene/dibutyl ether volume ratio may forexample vary between 75:25 and 35:65.

When the chlorobenzene/dibutyl ether ratio decreases, the bulk densityof the polyolefine powder prepared with the aid of the catalyst becomeslower and when the chlorobenzene/dibutyl ether ratio increases, theamount of the dissolved reaction product I becomes lower. Consequently,the best results are obtained when the chlorobenzene/dibutyl ethervolume ratio is between 70:30 and 50:50.

Small amounts of iodine and/or alkyl halides can be added to cause thereaction between the metallic magnesium and the aromatic halide RX toproceed at a higher rate. Examples of alkyl halides are butyl chloride,butyl bromide and 1,2-dibromoethane. The reaction temperature for step anormally is between 20 and 150° C.; the reaction time between 0.5 and 20hours.

After the reaction is completed, the dissolved reaction product I isseparated from the solid residual products.

During step b of the reaction, the dissolved reaction product I,obtained on carrying out step a of the reaction, is brought into contactwith an alkoxy group or aryloxy group-containing silane compound. Thisis accomplished by adding the alkoxy group or aryloxy group-containingsilane compound to the dissolved reaction product I at a temperature offrom -20 to 20° C. Preferably at a temperature of from -5 to 5° C.Preferably, reaction product I is contacted with the alkoxy group oraryloxy group-containing silane compound in the presence of an inerthydrocarbon solvent such as the solvents mentioned as dispersant in thediscussion of step a. Preferably, step b is carried out with stirring.The Si/Mg molar ratio during step b may vary from 0.2 to 20. Preferably,the Si/Mg molar ratio is from 0.4 to 1.0. The product from step b isrinsed with an inert hydrocarbon solvent and then used for thepreparation of the catalyst.

The following examples of alkoxy group or aryloxy group-containingsilane compounds may be mentioned:

tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane,

tetraisobutoxysilane, tetraphenoxysilane, tetra(p-methylphenoxy)silane,tetrabenzyloxysilane,

methyltrimethoxysilane, methyltriethoxysilane,

methyltributoxysilane, methyltriphenoxysilane,

methyltriphenoxysilane, ethyltriethoxysilane,

ethyltriisobutoxysilane, ethyltriphenoxysilane,

butyltrimethoxysilane, butyltriethoxysilane,

butyltributoxysilane, butyltriphenoxysilane,

isobutyltriisobutoxysilane, vinyl triethyoxysilane,

allyltrimethoxysilane, phenyltrimethoxysilane,

phenyltriethoxysilane, benzyltriphenoxysilane,

methyltriallyloxysilane, dimethyldimethoxysilane,

dimethyldiethoxysilane, dimethyldiisopropyloxysilane,

dimethyldibutoxysilane, dimethyldihexyloxysilane,

dimethyldiphenoxysilane, diethyldiethoxysilane,

diethyldiisobutoxysilane, diethyldiphenoxysilane,

dibutyldiisopropyloxysilane, dibutyldibutoxysilane,

dibutyldiphenoxysilane, diisobutyldiethoxysilane,

diisobutyldiisobutoxysilane, diphenyldimethoxysilane,

diphenyldiethoxysilane, diphenyldibutoxysilane,

dibenzyldiethoxysilane, divinyl diphenoxysilane,

diallyldipropoxysilane, diphenyldiallyloxysilane,

methylphenyldimethoxysilane and chlorophenyldiethyoxysilane.

Preferably use is made of tetraethoxysilane. The preparation of thecatalyst is carried out by contacting, during a step c, the purifiedreaction product from step b with TiCl₄.

Preferably an electron donor is also present during step c. Examples ofelectron donors are carboxylic acids, carboxylic anhydrides, esters ofcarboxylic acids, halide carboxylic acids, alcohols, ethers, ketones,amines, amides, nitriles, aldehydes, alcoholates, sulphonamides,thioethers, thioesters, organic silicon compounds and organic compoundscontaining a heteroatom, such as nitrogen, oxygen and phosphorus.

Examples of carboxylic acids are formic acid, acetic acid, propionicacid, butyric acid, isobutanoic acid, acrylic acid, methacrylic acid,maleic acid, fumaric acid, tartaric acid, cyclohexanoic monocarboxylicacid, cis-1,2-cyclohexanoic dicarboxylic acid, phenylcarboxylic acid,toluenecarboxylic acid, naphthalene carboxylic acid, phthalic acid,isophthalic acid, terephthalic acid and trimellitic acid.

Anhydrides of the aforementioned carboxylic acids can be mentioned asexamples of carboxylic anhydrides, such as acetic acid anhydride,butyric acid anhydride and methacrylic acid anhydride.

Examples of esters of carboxylic acids that can be mentioned are butylformate, ethyl acetate, butyl acetate, ethyl acrylate, methylmethacrylate, isobutyl methacrylate, methylbenzoate, ethylbenzoate,methyl-p-toluate, ethyl-α-naphthoate, monomethyl phthalate, dibutylphthalate, diisobutyl phthalate, diallyl phthalate and diphenylphthalate.

Examples of halide carboxylic acids that can be mentioned are thehalides of the above carboxylic acids, such as acetyl chloride, acetylbromide, propionyl chloride, butanoyl chloride, butanoyl iodide, benzoylbromide, p-toluyl chloride and phthaloyl dichloride.

Examples of suitable alcohols are methanol, ethanol, butanol,isobutanol, xylenol and benzyl alcohol.

Examples of suitable ethers are diethyl ether, dibutyl ether, diisoamylether, anisole and ethylphenyl ether,2,2-diisobutyl-1,3-dimethoxypropane,2,2-dicyclopentyl-1,3-dimethoxypropane and2-ethyl-2-butyl-1,3-dimethoxypropane.

Examples of organic silicon compounds that are suitable as electrondonor are: tetramethoxysilane, tetraethoxysilane,methyltrimethoxysilane, methyltributoxysilane, ethyltriethoxysilane,phenyltriethoxysilane, diethyldiphenoxysilane.

Examples of organic compounds containing a heteroatom are2,2,6,6-tetramethylpiperidine, 2,6-dimethylpiperidine, 2-methylpyridine,4-methylpyridine, imidazole, benzonitrile, aniline, diethylamine,dibutyl amine, thiophenol, 2-methylthiophene, isopropyl mercaptan,diethylthioether, diphenylthioether, tetrahydrofuran, dioxane,dimethylether, diethylether, anisole, acetone, triphenylphosphine,triphenylphosphite, diethylphosphate and diphenylphosphate.

Preferably dibutyl phthalate is used as the electron donor.

The TiCl₄ /Mg molar ratio during step c preferably is between 10 and100. Most preferably, this ratio is between 10 and 50. The molar ratioof the electron donor, if used, relative to the magnesium in step c mayvary between 0.05 and 0.75. Preferably this molar ratio is between 0.1and 0.4.

During step c use is preferably made of a solvent of an aliphatic oraromatic hydrocarbon compound. Most preferably, the solvent is tolueneor chlorobenzene. The reaction temperature during step c is preferably80-150° C., most preferably 90-120° C. At higher or lower temperaturesthe activity of the catalyst of the invention is undesirably low. Theobtained reaction product is purified to obtain a catalyst.

The catalyst of the invention is suitable for the preparation ofpolyolefins by polymerizing an olefin in the presence of the catalystand an organometallic compound containing a metal from group 1, 2, 12 or13 of the Periodic System of the Elements (Handbook of Chemistry andPhysics, 70th Edition, CRC Press, 1989-1990). Preferably theorganometallic compound is an organoaluminium compound. As theorganoaluminium compound use is made of compounds having the formulaR_(n) AlX_(3-n), where X is a halogen atom, an alkoxy group or ahydrogen atom, R is an alkyl group or an aryl group and 1≦n≦3. Examplesof organoaluminium compounds are trimethyl aluminium, triethylaluminium, dimethyl aluminium chloride, diethyl aluminium chloride,diethyl aluminium iodide, diisobutyl aluminium chloride, methylaluminium dichloride, ethyl aluminium dichloride, ethyl aluminiumdibromide, isobutyl aluminium dichloride, ethyl aluminiumsesquichloride, dimethyl aluminium methoxide, diethyl aluminiumphenoxide, dimethylaluminium hydride and diethyl aluminium hydride. Anelectron donor may also be present during the polymerization of anolefin. Examples of possible electron donors are described above withrelation to the execution of step c of the preparation of the catalyst.Preferably an alkoxysilane is used as the electron donor during thepolymerization.

The molar ratio of metal relative to Ti during the polymerization mayvary from 0.1 to 2000. Preferably this ratio is between 5 and 300. Theconcentration of the electron donor in the polymerization mixture isbetween 0.5 and 5 mol/l.

The catalyst is suitable for the polymerization of mono- and diolefinscontaining from 2 to 10 carbon atoms, such as ethylene, propylene,butylene, hexene, octene, butadiene and mixtures thereof. The catalystis particularly suitable for the polymerization of propylene andmixtures of propylene and ethylene.

The polymerization can be carried out in the gas phase or in the liquidphase. In the case of polymerization in the liquid phase a dispersingagent is present, such as n-butane, isobutane, n-pentane, isopentane,hexane, heptane, octane, cyclohexane, benzene, toluene or xylene. Liquidolefin can also be used as a dispersing agent. The polymerizationtemperature is usually between 0° C. and 120° C., preferably it isbetween 40° C. and 100° C. The pressure during the polymerization isnormally between 0.1 and 6 MPa. The molecular weight of the polyolefinthat is formed during the polymerization is controlled by adding duringthe polymerization hydrogen or any other agent known to be suitable forthe purpose.

The polymerization can be carried out in continuous mode or batchwise.The polymerization can be carried out in several, successive steps. Thepolymerization can also be carried out by first effecting thepolymerization in the liquid phase and then in the gas phase.

The invention will be further elucidated with reference to the exampleswithout being limited hereto.

EXAMPLES Example I

Preparation of Reaction Product I

A three-necked flask, fitted with a reflux condenser and a funnel, wasfilled with magnesium powder (26 g, 1.07 mol). The flask was broughtunder nitrogen. The magnesium was heated at 80° C. for 1 hour, afterwhich a mixture of dibutyl ether (173 ml) and chlorobenzene (80 ml) wasadded. Then iodine (0.03 g) and n-chlorobutane (3 ml) were successivelyadded to the reaction mixture. After the colour of the iodine haddisappeared, the temperature was raised to 97° C. and chlorobenzene (250ml) was slowly added in 2.5 hours. The dark reaction mixture that wasformed in the process was stirred for another 8 hours at 97° C. Then thestirring and heating were stopped and the solid material was allowed tosettle for 48 hours. By decanting the solution above the precipitate,which contained reaction product I, a solution with a concentration of 1mol/l of the soluble reaction product I was obtained. This solution wasused in the further catalyst preparation.

Preparation of Reaction Product II

The solution of reaction product I (100 ml, 1 mol/l) was dosed to areactor. This solution was cooled to 0° C. and a mixture oftetraethoxysilane (TES) (11.2 ml) and dibutyl ether (38 ml) was added,with stirring, in 2 hours.

After the solution had been added the reaction mixture was kept at 0° C.for another 0.5 hour, with stirring, after which the temperature wasraised to 60° C. Then the reaction mixture was kept at 60° C. for 1hour, after which the stirring and heating were stopped and the solidsubstance was allowed to settle in 30 minutes. The supernatant wasremoved by decanting. The solid substance was rinsed five times using150 ml of heptane. A pale yellow solid substance, reaction product II(13.5 g), was obtained, suspended in 40 ml of heptane.

Preparation of the Catalyst

A reactor was brought under nitrogen and 300 ml of titaniumtetrachloride was dosed into it. Then the reaction mixture was heated to115° C. A slurry, containing 12 g of reaction product II in 36 ml ofheptane, and dibutyl phthalate (7.2 ml) were added and the reactionmixture was stirred at 115° C. for 2 hours. Then the stirring wasstopped and solid substance was allowed to settle for 30 minutes.

The supernatant was removed by decanting, after which a mixture oftitanium tetrachloride (150 ml) and chlorobenzene (150 ml) was added.The reaction mixture was again heated to 115° C. and stirred for 30min., after which the solid substance was allowed to settle for 30minutes. This last cycle was repeated one more time. The solid substanceobtained was rinsed five times using 300 ml of heptane of 60° C., afterwhich the catalyst, suspended in heptane, was obtained.

Polymerization of Propylene

(1) A stainless steel polymerization reactor was inertized with nitrogenand was then filled with dry heptane free of oxygen (290 ml). Thentriethyl aluminium (TEA) (1.2 mmol as a solution in 5 ml of hexane),phenyltriethoxysilane (0.06 mmol as a solution in 5 ml of hexane) andcatalyst (0.01 g as a slurry in 1 ml of hexane) were dosed. Furthermore55 nml of hydrogen was dosed and propylene was dosed until a pressure of0.2 MPa was reached. The reactor was then quickly brought topolymerization conditions, with stirring: temperature 70° C., pressure0.5 MPa. The polymerization was then allowed to take place under saidconditions for 2 hours. Then the pressure was reduced to atmosphericpressure. The reactor contents were drained, after which the powder wasseparated from the heptane. The polypropylene powder was now driedfurther in a vacuum drying stove. In this way, 67.3 g of polypropylenepowder was obtained (see Table 1).

Example II

The catalyst was prepared as described in Example I. Propylenepolymerization was carried out in a stainless steel reactor that wasinerted with nitrogen and was then filled with dry n-heptane free ofoxygen (5.5 l). Then 8 mmol of TEA, 0.4 mmol of phenyltriethoxysilaneand 0.071 g of catalyst were added as a slurry in 5 ml of n-heptane.Then the reactor was heated to 70° C. Propylene containing 2 vol. %hydrogen was dosed until a pressure of 0.8 MPa was reached for 2 hours.1065 g of polypropylene powder was obtained (see Table 1).

Example III

Preparation of Reaction Product I

Reaction product I was prepared as described in Example I, except thatdiisoamyl ether was used instead of dibutyl ether.

Preparation of Reaction Product II

Reaction product II was prepared as described in Example I, except thatthe tetraethoxysilane was added to the reactor in 70 minutes instead ofin 2 hours. 14.2 g of reaction product II was obtained.

Preparation of the Catalyst

The catalyst was prepared as described in Example I, except that 150 mlof titanium tetrachloride plus 150 ml of chlorobenzene were added to thereactor instead of 300 ml of titanium tetrachloride. The slurry,containing reaction product II (12 g in 36 ml of heptane) and dibutylphthalate (7.2 ml) were added. Thereafter the reaction mixture washeated to 115° C. The reaction mixture was kept at 115° C. for 1 hourinstead of 2 hours.

Polymerization of Propylene

Propylene was polymerized as described in Example I (see Table 1).

Example IV

Preparation of Reaction Product I

Reaction product I was prepared as described in Example I, except that32 g of magnesium powder was used instead of 26 g of magnesium powderand the reaction with chlorobenzene was carried out at 110° C. insteadof at 97° C. The solution obtained contained 1.67 mol/l of reactionproduct I.

Preparation of Reaction Product II

Reaction product II was prepared as described in Example I, except thatthe tetraethoxysilane was added to the reactor in 80 minutes instead ofin 2 hours.

Preparation of the Catalyst

The catalyst was prepared as described in Example I.

Polymerization of Propylene

The polymerization of propylene was carried out as described in ExampleI (see Table 1).

Example V

Preparation of Reaction Product I, Reaction Product II and the Catalyst

Reaction product I, reaction product II and the catalyst were preparedas described in Example IV.

Polymerization of Propylene

Propylene was polymerized in the gas phase in a stainless steel reactorat a constant propylene pressure and a constant temperature of 70° C.,in the presence of hydrogen. 0.8 mmol of TEA as a solution in 7 ml ofn-hexane, 0.04 mmol of phenyltriethoxysilane as a solution in 7 ml ofn-hexane, 0.012 g of catalyst as a slurry in 1 ml of n-hexane and 55 nmlof hydrogen were dosed into the reactor, after which gaseous propylenewas dosed until a pressure of 1.5 atm was reached. All this was carriedout at a temperature of 40° C. Then the temperature was raised to 70° C.and the propylene pressure to 5 atm. The polymerization took place for 2hours, after which 86.4 g of polypropylene powder was obtained (seeTable 1).

Comparative Experiment A

Preparation of Reaction Product I

Reaction product I was prepared as described in Example I, after whichthe solid substance and the solution of reaction product I were notseparated.

Preparation of Reaction Product II

Reaction product II was prepared as described in Example I, using themixture of the solid substance and the solution of reaction product I asreaction product I (100 ml of slurry, 0.2 mol Mg). 23.1 g of product Awas obtained.

Preparation of the Catalyst and the Polymerization of Propylene

These were carried out as described in Example I (see the Table).

Comparative Experiment B

Preparation of the Catalyst

Reaction product II was prepared in the same way as described above inExample I. Then reaction product II was brought into contact with2,2,2-trichloroethanol as follows: a slurry of reaction product II (6.3g) in heptane (50 ml) was introduced, under nitrogen, into athree-necked flask (300 ml) fitted with a reflux condenser, a stirrerand a dropping funnel. This slurry was stirred at room temperature and2,2,2-trichloroethanol (2.0 ml, 0.02 mmol) dissolved in n-heptane (11ml) was added in 30 minutes. After all the alcohol had been added, thetotal reaction mixture was stirred for one hour at 80° C. Then the solidsubstance was removed through filtration and was rinsed four times, atroom temperature, using n-hexane (100 ml each time) and twice usingtoluene (100 ml each time). The final product was then treated withtitanium tetrachloride and electron donor in the manner described abovefor the preparation of the catalyst in Example I.

Polymerization of Propylene

Finally, a polymerization was carried out with this product as describedabove for the polymerization of propylene in Example I (see Table 1).

Comparative Experiment C

Preparation of Reaction Product II

Reaction product II was prepared as follows: a three-necked flask,fitted with a reflux condenser and a funnel, was filled with magnesiumpowder (6 g, 0.25 mol). The flask was brought under nitrogen, afterwhich the magnesium was heated at 80° C. for 1 hour. Then 42.4 ml ofdibutyl ether (0.25 mol), 55.8 ml of tetraethoxysilane (0.25 mol), 15 mlof chlorobenzene, 2 ml of n-chlorobutane and 0.02 g of iodine weredosed.

Then the mixture was stirred at 80° C. until the colour of the iodinedisappeared, after which the mixture was heated to 120° C. and 70 ml ofchlorobenzene was added in 2 hours, after which the stirring wascontinued for another 4 hours at 120° C. The stirring was stopped andthe solid substance was allowed to settle in 30 minutes. The supernatantwas removed by decanting. The precipitate was rinsed four times usingn-heptane (250 ml) of 60° C. Reaction product II was obtained, suspendedin heptane.

The Preparation of the Catalyst

The catalyst was prepared as described in Example I, using the reactionproduct II obtained in the above reaction as reaction product II.

Polymerization of Propylene

Propylene was polymerized as described in Example I, using the catalystprepared as described above.

                  TABLE 1                                                         ______________________________________                                        Polymerisation results                                                          Ex-    CY                    BD        span                                 am-  kg of   kg of   APP   II    (kg/ d50  (d90 - d10)/                         ple     PP/g cat   PP/g Ti  (wt %)    (wt %)   m.sup.3)    (μm)                                                     d50                                ______________________________________                                        1    6.8     309     1.0   98.4  0.42 250  0.5                                  2          15.1      686      1.0      97.8    0.42            325                                                      0.5                                 3          6.4       246      0.9      97.2    0.36            950                                                      1.5                                 4          8.1       289      1.2      97.8    0.37            1180                                                     1.4                                 5          7.2       257      --     96.1    0.37            1160                                                      1.4                                  A          4.8       267      1.6      97.2    0.32            280                                                      1.8                                 B          6.7       279      1.0      98.5    0.41            260                                                      0.5                                 C          4.1       227      1.4      96.8    0.38            425                                                      3.3                               ______________________________________                                    

Measuring Methods:

The catalyst yield (CY) is the number of kg of propylene powder obtainedper g of catalyst or per g of Ti.

The weight percentage of atactic polypropylene (APP) was determined asfollows: 250 ml of the filtrate (y ml) obtained in separating thepolypropylene powder (x g) and the hexane was dried over a steam bathand then in vacuo at 60° C. That yielded z g of APP. The total amount ofAPP (q g) is: (y/250)*z. The weight percentage of APP is:(q/(q+x))*100%.

The isotacticity index (II) of the polypropylene powder was determinedas follows: 5 g of polypropylene powder was extracted with the aid ofn-heptane in a Soxhlet extractor for 4 hours. The weight percentage ofthe polypropylene powder that does not dissolve in the boiling n-heptaneis the isotacticity index.

The bulk density of the polypropylene powder (BD) was determined inaccordance with ASTM D 1895.

The d50 and the span were determined in accordance with ASTM D1921,method A.

What is claimed is:
 1. A method for polymerizing at least one olefincomprising:contacting said at least one olefin with a polymerizationcatalyst and an organometallic compound containing a metal from group 1,2, 12 or 13 of the Periodic System of Elements under effectivepolymerization conditions, wherein said catalyst is obtained by a methodconsisting essentially of (a) contacting metallic magnesium with anaromatic halide represented by RX, wherein R represents an aromaticgroup containing from 6 to 20 carbon atoms and X represents a halide,under conditions effective to obtain a reaction product I and solidresidual products, whereupon the reaction product I is separated fromthe solid residual products, (b) adding an alkoxy group or an aryloxygroup-containing silane compound to the reaction product I at atemperature of from -20° C. to 20° C. to obtain a precipitate whereuponthe precipitate is purified to obtain a reaction product II, and (c)subsequently contacting said reaction product II with a halogenizedtitanium compound comprising titanium tetrachloride to obtain a furtherproduct and purifying said further product to obtain said catalyst.
 2. Amethod according to claim 1, wherein said at least one olefin comprisespropylene.
 3. A method according to claim 1, wherein in (a) saidmetallic magnesium and said aromatic halide are contacted in thepresence of an inert dispersant and an ether.
 4. A method according toclaim 3, wherein said inert dispersant comprises aliphatic, alicyclic oraromatic solvents having 4-10 carbon atoms.
 5. A method according toclaim 3, wherein said ether is at least one member selected from thegroup consisting of diethyl ether, diisopropyl ether, dibutyl ether,diisobutyl ether, diisoamyl ether, diallyl ether, tetrahydrofuran, andanisole.
 6. A method according to claim 1, wherein in (a) said metallicmagnesium and said aromatic halide are contacted in the presence of atleast one ether.
 7. A method according to any one of claims 3, 4, 5 or6, wherein the aromatic halide and ether are used in a volume ratio inthe range of 75:25 to 35:65.
 8. A method according to claim 7, whereinsaid volume ratio is in the range of 70:30 to 50:50.
 9. A methodaccording to claim 1, wherein in (c) said reaction product II iscontacted with said halogenized titanium compound in the presence of anelectron donor.
 10. A method according to claim 9, wherein said electrondonor is dibutyl phthalate.
 11. A method according to claim 1, whereinthe aromatic halide is phenylchloride.
 12. A method according to claim1, wherein the alkoxy group or aryloxy group-containing silane compoundis tetraethoxysilane.
 13. A method for polymerizing at least one olefincomprising:contacting said at least one olefin with a polymerizationcatalyst and an organometallic compound containing a metal from group 1,2, 12 or 13 of the Periodic System of Elements under effectivepolymerization conditions, wherein said catalyst is obtained by a methodconsisting essentially of: (a) contacting metallic magnesium with anaromatic halide represented by RX, wherein R represents an aromaticgroup containing from 6 to 20 carbon atoms and X represents a halide,under conditions effective to obtain a reaction product I and solidresidual products, whereupon the reaction product I is separated fromthe solid residual products, (b) adding an alkoxy group or an aryloxygroup-containing silane compound to the reaction product I at atemperature of from -20° C. to 20° C. to obtain a precipitate whereuponthe precipitate is purified to obtain a reaction product II, and (c)subsequently contacting said reaction product II with a halogenizedtitanium compound comprising titanium tetrachloride to obtain a furtherproduct and purifying said further product to obtain said catalyst, andwherein said reaction products and said catalyst are not contacted witha halogen-containing alcohol.